Microcin C7 (McC) is a potent natural product antimicrobial produced by enterobacteria. McC enters the target cell using a Trojan horse strategy, in which the active portion of the antibiotic is coupled to a peptide carrier that faciliates import into target cell through active transporters. We have characterized several biosynthetic clusters that produce the same antibiotic component but with different peptide attachments. Presumably, changes in the peptide allow for import through different transport systems that are specific to different bacterial species. Here we seek to: i. install variations in the peptide carrer allowing the molecule to be taken up by diverse bacteria. ii. re-design the peptide carrier so that it can be more effectively imported into susceptible organisms.